1. Field of the Invention
The present invention relates to an apparatus for simulating the soil mechanical impedance on the root growth potential of plants. More specifically, the present invention relates to an apparatus for simulating the growth mechanism of natural root systems and for accurately predicting mechanical soil impedance on the growth of these root systems.
2. Description of the Prior Art
Agricultural producers have long recognized that proper soil tilth, adequate water and proper nutrition are essential for crop production. Procedures have long been established for characterizing moisture and nutritional deficiencies, and these procedures have been widely used for addressing problems at the field level. However, procedures for characterizing soil physical conditions relative to root growth potential have lagged. That is, it has in the past been difficult to accurately determine the degree to which the soil physical characteristics will fully or partially inhibit the plant root growth.
Numerous attempts have been made to measure these soil characteristics. On the most primitive level, it has been known to assess such parameters as wheel sinkage or load bearing capacity. More sophisticated parameters for measuring the soil physical conditions included the soil cohesion coefficient, the cone index friction angle and the bulk density. However, not only are these parameters difficult to measure, but they are not fundamentally sound indicators of the forces exerted by a root in the growth process.
The most widely used instrument for ascertaining the mechanical impedance of soil to root growth is the cone penetrometer, one example of which can been seen in U.S. Pat. No. 4,061,021 to Baldwin et al. Such cone penetrometers were developed for use in tillage and trafficability studies, rather than for root penetration impedance studies. However, they have been used in determining root penetration for impedance because of the lack of a more adequate apparatus. It has been found that the cone penetrometers provide sufficient accuracy to predict impedance values which are sufficient to severely inhibit root growth; however, they lack sufficient accuracy to correlate lesser degrees of mechanical impedance with a resulting partial constraint of growing conditions.